OvrflowinCHEESE

Hello I'm new here. I am trying to figure out an issue with my 96. My truck runs fine on the rear tank, but once i switch it over to the front tank it starts to spit and sputter out (especially up hill) but if i switch it back to rear for a couple of miles and switch it back its fine for a while, or at least until I fight another uphill drive. Any advice is helpful.

golfmechanic26

I assume there is fuel in both tanks lol.

It could be the fuel pump. Takes more fuel to go up hills and the pump may be worn out.

Chris_1

iTrader: (1)

Sounds like the front pump is dying.

joegeds

I agree with the other posters here - you're front fuel pump is going. Mine does the exact same thing. Under any kind of load, it sputters out and I have to switch to rear. are you having issus with fuel filling the front tank while using the rear? Because that is next. The diaphragm in the front Fuel Delivery Module will fail and fuel that is suppse to return to the rear tank (when you are running the rear tank) will fill up the front to the point of over flow.

golfmechanic26

Idk if that happens everytime though like that. My fuel pumps are fine and I have that issue on my truck when I fill the rear tank. It always drains into the front. Also, the fuel is returning to the rear like it should because I usually fill the front and can always run on the rear tank for a little while after I run on the front for a couple days.

Chris_1

iTrader: (1)

92-96 (those years for sure anyway) don't have a switching valve. They just rely on the 1 way check valves in the pump. Power to the front pump, pressure goes to the rear tank but is stopped by the rear pump check valve so all the pressure is directed to the fuel rail and vice versa for power to the rear pump. As the check valves start to fail, the tanks will cross fill, also fuel pressure drops even though the pump that is activated may be in perfect condition.
As for what happens to direct fuel from the regulator to the proper tank - I don't know, I've never really checked into it that far. Maybe the activated pump has a valve for the return line ? That's just a guess - maybe if someone else knows the answer to that one they could post it. Now that I've thought about it, I'd kinda like to know how that works.

Chris_1

iTrader: (1)

OK, I had to know so I looked it up.
There's a shuttle valve in each pump as well as a check valve. The pressure that the pump makes when it's running opens the shuttle valve so that fuel from the return line returns to the tank that is pumping.
When the pump is not producing pressure the shuttle valve is closed.
The check valves are simply a one way valve, the pump can draw fuel through it but it can't go back to the tank through the check valve.
So basically the only controls in the dual tank system are the 2 fuel pumps, the pressure regulator and the switch on the dash.
Each pump has an electric motor, a check valve and a shuttle valve. The switch on the dash turns on this pump or that pump. The pressure regulator opens when vacuum is high to return excess pressure to the tank that is selected.
That should make troubleshooting a fuel system fairly basic.

OvrflowinCHEESE

Thank you for the advice. I do know when I run the rear tank it does fill the front. I usually only put 3/4 in the front and a full tank in the rear. Next question... Where can I find camber adjusters for the front wheels. I put new front springs and shock in the front, it took leveled it out but seriously messed with the camber.

fltdriver

Amazon is the cheapest place I found, you want two , I linked it so all you have to do is click on the part number. Very easy to install, just drop them in set at true zero, put everything back, and get an alignment, or if you are cheap like me just get the printout from the alignment shop and use the chart that comes with them to adjust yourself. So long as your toe is in spec it's very very simple to do yourself and you will save over 50% on the cost of the alignment.